1. Field of the Invention
The present invention relates generally to a door lock having a spring-projected slide bolt, a handle for retracting the bolt, and a key control for selectively permitting and preventing the handle from retracting the bolt. More particularly, the invention relates to a lock of this type including a key-controlled disconnect linkage for selectively drivingly connecting and disconnecting the handle and the bolt, whereby the handle is, at all times, freely movable between normal and operating positions, but is functional only when the key control is "unlocked" to enable the handle to retract the bolt.
While the present invention has particularly advantageous use in conjunction with flush-type door locks used on swinging doors of vehicles, industrial cabinets, electrical equipment enclosures and the like, principles of the invention are not limited in application to such uses.
2. Prior Art
Flush-type door locks including a body, a lock bolt slidably carried on the body, and an operating handle for moving the bolt relative to the body are well known. Normally the handle is in a flush or nested position when the bolt is projected. Bolt retraction is effected by pivoting the handle to an operating position. Locks of this type are well suited for use on swinging doors of vehicles such as trucks, on merchandise, tool and equipment cabinets, electrical equipment enclosures and the like.
Flush-type, paddle-handle door locks employing key-operated rotatable cams for selectively permitting and preventing unlocking movements of operating handles, and having spring-projected slide bolts, are described in U.S. Pat. Nos. 3,707,862, and 3,668,907 granted Jan. 2, 1973 and June 13, 1972, respectively, to John V. Pastva, Jr. An ornamental appearance employed in locks of this general type is illustrated in U.S. Design Pat. No. 230,132 issued Jan. 29, 1974 to John V. Pastva, Jr.
The provision of a handle disconnect feature in a door lock is desirable in that the presence of such a feature will lessen, if not totally eliminate, incidents of these locks being damaged by would-be intruders. Since the handles of most previously proposed door locks are restrained from moving when the locks are locked, it is common for would-be intruders to attempt to gain entry by applying excessive leverage force to the lock handles. Where handle disconnect features are provided, the lock handles may always be moved freely, but are functional to retract the bolt only when the locks are "unlocked." Locks having handle disconnect features can be made practically entry-proof short of the application of such forces as will totally destroy the locks.
Door locks employing various types of handle disconnect systems have been proposed. Prior proposals have, however, suffered from a variety of drawbacks including complexities of construction; failures to mount all of the operating parts of a lock on a single body member so that the resulting locks form compact, easy to install units; and inappropriately configured parts of sizes and shapes that prohibit installation of locks embodying such proposals in conventionally configured door lock mounting openings.